NAME OF SCHOOL

IB Psychology Standard Level

Internal Assessment The Effect of Interfering Word Stimuli upon

Naming Colours Serially

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Candidate Name: Ibpsychrevision.blogspot.com

Candidate Number: XXXX XXX

Instructor: Ibpsychrevision.blogspot.com

Date of Submission: dd/mm/yy

Word Count: 1496

Table of Contents

Abstract ................................................................................................................................................... 1

Introduction ............................................................................................................................................ 2

Method ................................................................................................................................................... 3

Design .................................................................................................................................................. 3

Participants ......................................................................................................................................... 3

Materials ............................................................................................................................................. 3

Procedure ............................................................................................................................................ 4

Results ..................................................................................................................................................... 4

Discussion................................................................................................................................................ 6

References .............................................................................................................................................. 7

Appendices .............................................................................................................................................. 8

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Abstract

The aim of this experiment was to investigate the level of interference on attention when naming

colours in conflicting word-colour stimuli compared to naming colours serially – the Stroop effect.

The lab experiment was a partial replication of J.R. Stroop’s experiment 2 (1935). The independent

variable was the colour stimulus named by participants. It used two tests: naming coloured squares

serially (NC) and naming coloured words with interfering word stimuli (NCWd). The dependent

variable was the reaction time taken by participants to recognise and name the colours. The findings

showed a causal relationship between the NC and NCWd tests. The results indicate that naming a

coloured word (“RED” in green ink) takes significantly longer than naming colours serially. The

interference is caused by the introduction of the conflicting word stimulus. It reaches the conclusion

that the automaticity of reading inhibits attention in naming colours serially when an interfering

word stimulus is introduced because it activates a schema. However, further language

considerations are necessary for a cross-cultural understanding of the Stroop effect.

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Introduction

The cognitive perspective focuses on the underlying mental processes that influence

behaviour. It is particularly interesting in factors that impede or facilitate information processing

such as attention. Attention is the ability to concentrate on a specific stimulus thus enabling the

processing of information (Colman, 2003). Attention can be affected by many factors such as trying

to block out other thoughts while attempting to focus on a particular stimulus or disabling automatic

processes such as reading. The ability to focus on a specific stimulus is affected by schemas – an

active mental organisation of information based on prior experience. Focusing on a specific stimulus

becomes difficult with conflicting stimuli such as words and colours or multiple languages.

When conflicting stimuli are presented, the mind tends to focus on what is important; based

on previous experience stored in schemas. The recognition and processing of the semantic meaning

of a word stimulus becomes an automatic task after practice. Reading thus interferes in naming

colours if paired with a word stimulus when the task is to name the colour and ignore the semantic

meaning of the word.

The Stroop task (Stroop, 1935) investigated interference in attention on naming colours.

Stroop’s second lab experiment investigated the effects of interfering word stimuli on naming

colours serially. The colour stimulus was the independent variable and the reaction time taken to

name the colours was the dependent variable. He studied naming colours serially using solid

coloured squares as the control stimulus (NC test). Afterwards, Stroop introduced the interfering

word stimulus: incongruent word-colour pairs (“GREEN” in red ink, NCWd test). He found that the

time taken to name colours in the NCWd test was significantly higher. This delay in reaction time

due to the word and its conflicting ink colour is termed interference – a type of error that might

occur in the Stroop effect because of the faulty activation of a schema. The findings suggest that the

automaticity of reading inhibits the ability to focus on the colour stimulus. Preston and Lambert

(1969) studied the Stroop effect in bilinguals, and found that relative proficiency in different

languages affects the level of interference.

The aim of this experiment is to investigate interference in attention. The reaction time is

the delay in focusing and naming the colour stimulus. The interference is measured as the

difference in reaction time between naming colours serially (NC) and naming colours with interfering

word stimuli (NCWd). This is achieved by a partial replication of Stroop’s original study (Stroop,

1935b).

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Method

Design

The experimental design was a laboratory experiment. It used the same experimental group

and one repeated measure. Participants performed both tests individually one after another to

establish a causal relationship. The independent variable was the colour-stimulus. In the control

Naming Colours test (NC) the colour stimulus was a 24-point coloured square (). In the Naming

Coloured Words test (NCWd), the colour stimulus was a word-colour in an incongruent colour (e.g.

“GREEN” in red ink). The dependent variable was the reaction time taken by participants to name

the colours. Participants were not allowed to leave any errors uncorrected during NCWd.

Non-psychology students were used to avoid possible demand characteristics. This assisted

in avoiding the confounding variable of previous practice.

Before the experiment participants were briefed about the nature of the experiment. Each

participant signed a consent form that explained their rights for the duration of the experiment. The

experiment consistently maintained considerations to avoid any possibility of physical and/or

psychological harm. After the experiment participants were debriefed about the aim of the

experiment. Contact information was collected and the experimenters’ email addresses were

provided in case the participants had any concerns after the experiment.

Participants

The target population was Danish students at Nyborg Gymnasium studying the Danish

Studentereskamen1. The school is roughly split between both genders ages 16 to 20 years old.

Experimenters found several classes that were half male and half female. All 3 classes are partially

representative of the target population. The first class (3c) asked agreed to participate and

contained 9 males and 9 females (n=18) all aged 19. Because of age restrictions (>16 without

parental consent) and convenient class schedules 3c was used as an opportunity sample. Colour-

blindness was not an issue. Because the experiment requires a repeated measure, participants

remained in the same experimental group.

Materials

Informed Consent Form2

1 Danish diploma to enter higher education

2 See Appendix 1 (p. 8)

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Standardised Instructions / Briefing Note3

Debriefing Note4

A4 Sheet for NC test5

A4 sheet for NCWd test6

Stopwatch

Procedure

The experiment was conducted in a quiet, well-lit room. Participants are seated and given

two minutes to allow their eyes to adjust to lighting conditions while they read and sign the consent

form. Afterwards a short briefing of the experiment along with standardised instructions for ethical

considerations was read, including the right to withdraw at any time.

Participants were instructed to name the colours as fast as possible following Western

reading order (from left to right) for both tests. The A4 sheet for the NC test is presented to

participants and their time taken to name the colours was recorded. Afterwards participants were

told that if they made errors during the NCWd test, they would have to try again until they named

the correct colour before proceeding. The A4 sheet for the NCWd test was then presented and the

time taken to name the colours was recorded.

Upon completion participants received written debriefing explaining the aim of the

experiment, right to ask questions and view the final report. It also contained the experimenters’

contact information.

Results

The score recorded after each test was verbally confirmed by both experimenters. The raw

data was collected in one table7.

The overall reaction time for the NC test ranged from ≈ 9 to ≈ 22 seconds (range ≈ 13). The

range for the NCWd test was significantly higher ≈ 17 to ≈ 46 seconds (range ≈ 29).

3 See Appendix 2 (p. 8)

4 See Appendix 3 (p. 8)

5 See Appendix 4 (p. 9)

6 See Appendix 5 (p. 9)

7 See Appendix 6 (p. 9)

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The mean reaction times and standard deviation calculations for both tests were used

because reaction times are interval data8. Mean scores are the average reaction times taken by

participants and the standard deviation is a measure of the dispersion of the data (see Table 1).

Table 1: Mean, Standard Deviation and Range for NC and NCWd Tests

Test Mean (s) Standard Deviation (s) Range ≈ (s)

Control (NC) 14.176 3.780 13

Interfering Word Stimulus (NCWd) 31.088 6.904 29

The calculations show a significant difference between both the mean scores and the

standard deviations for each test. The percentage mean difference of the NCWd test was 119.298%

higher than the NC test; more than twice as long9. These calculations show a clear causal

relationship as expected. Figure 1 illustrates this difference.

Figure 1: Mean for NC and NCWd Tests

The mean percentage difference between NC and NCWd is termed the Stroop Effect – the

interference in attention caused by the stimulus change from naming colours serially (NC) to

interfering word-colour pairs (NCWd).

8 See Appendix 7 (p. 10)

9 See Appendix 8 (p. 10)

0

5

10

15

20

25

30

35

Naming Colours (NC) Naming Coloured Words(NCWd)

Tim

e t

ake

n (

sec)

Colour Stimulus (Independent Variable)

Mean Times for NC and NCWd Tests

Mean

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Discussion

The findings of this experiment coincide with Stroop’s 2nd experiment; the automaticity of

processing words inhibits attention from naming colours in the NCWd test. However, the mean

difference Stroop observed was 75% compared to 119% in this experiment. Possible reasons for this

are bilingualism. All participants were studying the Studentereksamen, so experimenters assumed

Danish was their strongest language. It was evident that several students had a non-Nordic

background and it is possible that Danish was not their native tongue. The Western reading order

may have troubled ethnic participants if reading from right to left dominated their schema. This

aspect of their schemas might have further increased their level of interference. Future studies

should include this cultural difference.

Experimenters used consistent conditions for each participant, so any errors incurred were

consistent. Stroop’s original experiment did not use an equal amount of males and females to

account for gender differences. Demand characteristics were addressed to correct the extraneous

variable of familiarity and previous practice. However, practice does not significantly reduce the

level of interference (Stroop, 1935c). Nonetheless, demand characteristics should be addressed in

future studies of similar nature. Colour-blindness must be addressed to avoid unreliable data.

Linguistic symbols (*, &) may serve as a more appropriate control (Stroop, 1935c) than

coloured squares. This stimulus change would confine both tasks to a similar set of symbols.

However any similarity between symbols used should be distinct from letters used in different

languages (e.g. Arabic, Russian) to avoid possible confusion in schemas.

Testing both genders from different cultures and all age groups in Nyborg Gymnasium,

stratified by ethnicity and age would allow for a more reliable and comprehensive sample.

Participants should be asked what their native tongue is along with proficiency in other languages to

account for bilingual differences in future experiments.

The evidence suggests that the automaticity of reading inhibits attention from naming

colours when the interfering word-colour stimulus is introduced. However further considerations

for different reading orders in other languages (Arabic) are necessary for a cross-cultural

understanding of The Stroop Effect.

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References

Colman, A. M. (2003). Oxford Dictionary of Psychology. New York: Oxford University Press.

Glassman, W. E., & Hadad, M. (2006). Approaches to Psychology (4th Edition ed.). Berkshire,

England: Open University Press.

Macleod, C. M. (1991). Half a Century of Research on the Stroop Effect: An Integrative Review

[Electronic Version]. Psychological Bulletin , 109 (2), 163-203.

Stroop, J. R. (1935). Studies of Interference in Serial Verb Reactions [Electronic Version]. Journal of

Experimental Psychology , 18 (6), 643-662.

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Appendices

Appendix 1

Consent Form (translated; signed by participants)

I hereby understand the following:

1. The nature of the experiment has been satisfactorily explained

2. My identity and anonymity will be protected

3. The right to withdraw for any reason is at my disposal and the reason need not be disclosed

4. I will not receive any form of compensation for my participation

5. The experiment will be conducted in a non-derogatory manner

6. I will be fully debriefed afterwards and have the opportunity to see the results and ask any

questions

The undersigned gives his/her informed consent to participate in this experiment

Signature ____________________________ Date_____________

Contact Number ______________________

Appendix 2

Briefing/Standardised Instructions (translated)

“You are about to participate in a psychology experiment. We will be testing your reaction time in

naming colours serially. You have the right to withdraw from this experiment at any stage. Your

name, age and identity will remain confidential. At the end of the experiment you will be fully

debriefed. During the first test, please name the colour squares you see on the sheet of paper from

left to right, starting at the top left corner. Continue in the same manner for the following rows. For

the second test please name the colour of the ink the word is printed in. Name the colours as fast as

you can. If you make a mistake we will ask you to try again before proceeding. If you have any

questions or concerns please address them now. Are you ready to begin?”

Appendix 3

Debriefing (translated)

“The aim of our experiment was to test your reaction time in naming colours. More specifically we

measured the interference of interfering word stimuli in your overall reaction time between the first

and second test. Your results were highly beneficial to our experiment and we value and appreciate

your participation. Our email addresses are provided below in case you have any concerns or

questions and so that you may request a copy of the finished report if you wish to read it.

ibpsychrevision.blogpot.com Mobile: XX XX XX XX

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Appendix 4

Table used for NC test (landscape orientation, scaled to fit)

Appendix 5

Table used for NCWd test (landscape orientation, scaled to fit)

LILLA BLÅ GRØN RØD BRUN

RØD BRUN BLÅ GRØN LILLA

BRUN RØD GRØN LILLA BLÅ

BLÅ GRØN LILLA BRUN RØD

LILLA GRØN RØD BLÅ BRUN

Appendix 6

Raw data for NC and NCWd

Participant No. Gender NC Test (sec) NCWd Test (sec)

1 Female 22.390 29.782

2 Female 16.360 25.157

3 Female 10.812 46.344

4 Female 15.750 34.109

5 Female 17.094 31.188

6 Female 12.625 31.719

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7 Female 11.891 29.828

8 Female 11.437 34.954

9 Female 10.844 22.860

10 Male 16.281 34.750

11 Male 18.140 36.594

12 Male 21.172 31.281

13 Male 13.656 33.609

14 Male 11.187 34.813

15 Male 14.000 38.735

16 Male 11.797 20.547

17 Male 9.140 17.453

18 Male 10.594 25.859

Appendix 7

Statistical Calculations

Mean: 1

1 n

X i

i

Xn

: 255.17, 18x n Naming Colours (NC)

255.17 14.176118

seconds

d 559.582, 18x n Naming Coloured Words (NCW ):

559.582 31.087918

seconds

Mean percentage difference:31.0879 14.1761 100 119.298%

14.1761

Range percentage difference:29 13 100 123.076%

13

Appendix 8

Standard Deviation Calculations

2

1

( )ni

X

i

X X

n

Standard deviation for NC: 3.780 seconds

Standard deviation for NCWd: 6.904 seconds